BIL deleted me about 18 months ago now. I've only seen him once since then and neither of us mentioned it, and now he's emigrated anyway so it's likely that we will never speak of it.
I was a bit surprised and pissed off, but really, we are not 13, it's not the end of the world, so I told myself to get over it and that was that.
The reason I think he deleted me is because I didn't go to PIL's anniversary party as we are not on speaking terms. DH only told me about the party on the day it was due to take place and I told him to go but he didn't want to. PILs have told a lot of lies about me, have disowned DH more than once, and caused a lot of trouble but they also cannot understand why we are upset and angry with them and find it baffling that we would not go and celebrate with them (my being called a bitch by MIL, them wishing DH had never met me and them telling DH that he was a tiny part of their lives that they considered to be over now might have had something to do with it, to say nothing of their offensive comments about the babies we lost).
The reason I was pissed off with him is that he has never asked for my side of the story and because I don't have MIL's habit of ringing the entire family to cry and weep and insist they take sides, I've never given him my side. He's believed MIL's lies and the only comment he has ever made on it was passed on to me by his wife, who said he knows what his mother can be like but that she is too old to change so we all just have to accept her behaviour.
This is the strangest deletion I have had though. Recently I was deleted by a friend because I liked a picture from a group that had the word 'llama' in the group name. A few mutual friends were liking pictures and quotes from this group and this particular person had suddenly decided that it meant we were all in fact secretly and sneakily calling her a llama by stealth. "But why would all be talking about llama's if you didn't mean me?" She deleted us all, convinced that dramallama-gate, as it is now known, was all about her 